A bureau investigator (局員捜査官, kyokuin sōsakan) is a person assigned to the CCG offices. They do not carry quinque, but rather Q bullets and firearms. They can be considered backup for the ghoul investigators and are only called on when quantity is more important than quality. They also handle the majority of the paperwork in the CCG.
They are trained at the Ghoul Countermeasures Training Center and likely form the majority of the CCG employees. Upon graduation from the Ghoul Countermeasures Training Center they begin as Rank 3 investigators and are assigned to a branch office in one of the wards of Tokyo, whereas a ghoul investigator is assigned to the 1st ward office, the CCG Main Office, and travel as necessary. Bureau investigators do, however, follow the same rules and must act accordingly to the Ghoul Countermeasures Law as strictly as ghoul investigators.